Myocardial infarction is a major cause of morbidity and mortality in the United States and most developed countries. Heart transplantation is an effective therapeutic modality in reconstituting the function of damaged heart. However, widespread application of this modality is severely limited due to the scarcity of organ donors and complications associated with the required immunosuppression. Cell therapies aiming at replacing infracted heart muscle are highly desirable. Recent advances in the generation of patient-specific human induced pluripotent stem cells (hiPSCs) have sparked hopes that these cells can serve as an inexhaustible source of cellular material for repairing damaged myocardium. Like human embryonic stem cells (hESCs), hiPSCs have been shown to differentiate towards functional cardiomyocytes utilizing embryoid body (EB) culture and serum-supplemented media. Nonetheless, clinical realization of stem cell-based therapies for heart repair will require the production of hiPSC-derived cardiomyocytes (i) using directed differentiation methods free of animal components (e.g. serum), and (ii) in large numbers. We hypothesize that hiPSCs can be directed towards cardiomyocyte-like cells with physiologically relevant factors known to participate in embryonic heart development. To that end, we propose to establish a method for the directed differentiation of hiPSCs to stem cardiac cells in static cultures (e.g. dishes). However, the propagation and differentiation of iPSCs in dishes are challenging to scale-up. We have discovered that hESCs cultivated in a bioreactor can be expanded several fold and differentiate to multiple lineages. Then, our second hypothesis is that hiPSCs cultured on microcarriers in stirred-suspension bioreactors can also be propagated to high concentrations. We propose to culture hiPSCs in a stirred bioreactor culture system and determine conditions which favor the growth of hiPSCs without compromising their pluripotency and viability. Furthermore, stem cell differentiation to cardiac cells is typically carried out in EB cultures. Given that not all cells within EBs are exposed to cardiogenic factors, this process is challenging to control and is characterized by poor efficiency. Therefore, expansion of hiPSCs on microcarriers may be followed by switching to conditions directing the cells to adopt a cardiomyocyte fate. We will evaluate the cardiogenic potential of hiPSCs cultured in microcarrier bioreactors. The resulting cells will be characterized for the expression of cardiomyocyte-associated genes/proteins and will be subjected to functional assays in vitro. Lastly, a mouse infarct heart model will be employed to evaluate the functional attributes of hiPSC-derived heart cells in vivo. This study will yield new information benefiting the development of bioprocesses for the generation of large quantities of hiPSC-derived cardiomyocytes suitable for heart therapies. PUBLIC HEALTH RELEVANCE: Myocardial infarction-induced heart failure is a prevailing cause of death in the United States and clinical therapies aiming at replacing or restoring damaged heart muscle are lacking. Patient-specific human induced pluripotent stem cells, which proliferate extensively and can differentiate towards functional cardiomyocytes, may serve as a renewable cellular source for regenerative heart therapies. This project seeks to further our understanding of the cardiogenic potential of human induced pluripotent stem cells in static and scalable culture systems and to advance bioprocess technologies for the production of stem cell-derived cardiomyocytes in clinically relevant quantities.